The present invention relates to an ink-jet head and a method for producing an ink-jet head.
Conventionally, as an ink-jet head, one produced by bonding a nozzle plate defining a plurality of nozzles to a head body is known. The head body of this type of ink-jet head includes a plurality of pressure chambers storing ink, ink channels communicating with the pressure chambers, and actuators for applying pressure to the ink in the pressure chambers. The nozzle plate is bonded to the head body so that the respective nozzles communicate with the corresponding ink channels. With application of pressure to the ink in the pressure chambers, part of the ink in the pressure chambers flows through the ink channels and is discharged out from the nozzles as ink droplets.
An adhesive is often used for the bonding between the nozzle plate and the head body. During this bonding, various problems arise due to the smallness of the sizes of the nozzle plate and the head body. That is, if an excessive amount of an adhesive is applied, the adhesive may protrude into the ink channels, blocking smooth flow of ink, and this may cause discharge failure. In addition, if an air bubble is mixed in the adhesive, the air-trapped bubble portion of the adhesive fails to provide sufficient adhesion, and this may cause bonding failure.
To prevent the problems described above, various techniques have been proposed. For example, Japanese Laid-Open Patent Publication No. 5-330067 discloses providing an escape groove for an adhesive in a head body, for prevention of protrusion of the adhesive into ink channels. Japanese Laid-Open Patent Publication No. 2001-63052 proposes a head body constructed of a plurality of channel plates stacked on each other, in which a through hole for escape of the air is formed in the direction of the stacking of the channel plates.
In the conventional ink-jet heads disclosed in the publications described above, the escape groove or the through hole must be provided in the head body. This complicates the structure of the head body, and thus causes reduction in yield and increase in production cost.
A thermosetting adhesive may be used as the adhesive for the ink-jet head. In this case, a by-product such as water may be generated in the process of dry setting. It is however difficult to effectively discharge such a by-product in the conventional ink-jet heads described above, in which an adhesive is solidly applied to the entire surface of the head body or the nozzle plate.